Douglas Isbell
Headquarters, Washington, DC June 23, 1998
(Phone: 202/358-1753)
RELEASE: 98-109
LEWIS SPACECRAFT FAILURE BOARD REPORT RELEASED
NASA's Earth-orbiting Lewis spacecraft failed last fall
due to a combination of a technically flawed attitude-control
system design and inadequate monitoring of the spacecraft
during its crucial early operations phase, according to the
report of the Lewis Spacecraft Mission Failure Investigation
Board.
Lewis was launched on August 23, 1997, with the goal of
demonstrating advanced science instruments and spacecraft
technologies for measuring changes in Earth's land surfaces.
The spacecraft entered a flat spin in orbit that resulted in
a loss of solar power and a fatal battery discharge. Contact
with the spacecraft was lost on Aug. 26, and it then re-
entered the atmosphere and was destroyed on Sept. 28. The
890-pound spacecraft was designed and built by TRW Space &
Electronics Group, Redondo Beach, CA, as part of NASA's Small
Spacecraft Technology Initiative.
The design of the Lewis attitude control system was
adapted by TRW from its design for the system on the Total
Ozone Mapping Spectrometer spacecraft. The failure board
found that this adaptation was done without sufficient
consideration for applying the system's design to a different
primary spacecraft spin-axis orientation on Lewis. As a
result, minor rotational perturbations, possibly due to small
imbalances in the forces produced by the spacecraft's
attitude control thrusters, caused the Lewis spacecraft to
enter a spin. This situation eventually overloaded the
spacecraft's control system while it was in a safehold mode.
Prelaunch simulation and testing of the spacecraft's safehold
modes also was flawed because it failed to analyze this
possibility, the failure board found.
The combination of these errors with the subsequent
assumption that a small crew could monitor and operate Lewis
with the aid of an autonomous safehold mode, even during the
initial operations period, was the primary cause of the
mission failure, according to the failure board's report.
The failure board also assessed the role of the "faster,
better, cheaper" project management approach in the Lewis
program.
"The Lewis mission was a bold attempt by NASA to
jumpstart the application of the 'faster, better, and
cheaper' philosophy of doing its business," said Christine
Anderson, chair of the failure board and Director of Space
Vehicles for the U.S. Air Force Research Laboratory at
Kirtland Air Force Base, NM. "I do not think that this
concept is flawed. What was flawed in the Lewis program,
beyond some engineering assumptions, was the lack of clear
understanding between NASA and TRW about how to apply this
philosophy effectively. This includes developing an
appropriate balance between the three elements of this
philosophy, the need for well-defined, well-understood and
consistent roles for government and industry partners, and
regular communication between all parts of the team."
"The Lewis failure offers us some valuable lessons in
program management and in our approach to technical
'insight.' Lewis was an extreme example of allowing the
contractor to have engineering autonomy. In the end,
however, NASA has the responsibility to assure that the
project objectives are met, and our assurance process was
ineffective in this case," said Dr. Ghassem Asrar, NASA
Associate Administrator for Earth Science. "NASA's Office of
the Chief Engineer is developing general 'lessons learned'
from this project and other 'faster, better, cheaper'
efforts, and we intend to apply them vigorously to all of our
future missions, including the second generation of
spacecraft in the Earth Observing System.
"I would like to commend Christine Anderson and the
members of her panel for their thorough job, and thank all
the participants in the Lewis program for their cooperation
with this review," Asrar added.
The total cost to NASA of the Lewis mission, including
its launch vehicle and one year of planned orbital
operations, was $64.8 million. NASA incurred an additional
cost of $6.2 million for storage and maintenance of the
spacecraft during a one-year delay due to launch vehicle
issues.
Lewis was part of NASA's Earth Science enterprise, a
long-term research program designed to study the Earth's
land, oceans, air, ice and life as a total system.
-end-
EDITOR'S NOTE: The report of the Lewis Spacecraft Mission
Failure Investigation Board is available via the Internet at
the following address:
http://arioch.gsfc.nasa.gov/300/html/lewis_document.pdf